Process for purifying inert gases

Abstract

The invention relates to a process for the purification of an inert gas by subjecting the inert gas to a sorption treatment, especially gas scrubs. The invention comprises compressing the inert gas to a higher pressure before the sorption treatment, performing the sorption treatment at this higher pressure, and then expanding the purified inert gas. The advantages of the process of the invention can be seen to be essentially that, for example, streams of waste air which contain as impurities volatile solvents such as methyl chloride, isopropyl chloride, or dichloromethane, can be cleaned up with low consumption of energy and scrubbing liquid. Correspondingly, the equipment can have smaller dimensions.

We claim: 
     
       1. A process for purifying an inert gas having condensable impurities to produce a purified inert gas, by subjecting the inert gas to a sorption treatment, which comprises compressing the inert gas to a higher pressure to at least partially condense and separate the condensable impurities of the inert gas before the sorption treatment and carrying out the sorption treatment at this higher pressure, and expanding the purified inert gas, thereby removing the condensed impurities, wherein the inert gas is an organic solvent-containing waste air, the sorption treatment is an absorption process with a liquid sorbent, and the sorbent comprises a glycol ether or a mixture of glycol ethers which are selected from the group consisting of polyethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, pentaethylene glycol dimethyl ether, polyethylene glycol dibutyl ether and diethylene glycol dibutyl ether. 
     
     
       2. The process of claim 1, wherein the sorbent is purified in a regeneration stage after the sorption treatment. 
     
     
       3. The process of claim 1, wherein the energy used for compression is at least partly recovered after the sorption treatment. 
     
     
       4. The process of claim 1, wherein the inert gas is cooled after compression. 
     
     
       5. The process of claim 4, wherein the cooling effect produced by the expansion is used for cooling purposes. 
     
     
       6. The process of claim 1, wherein the inert gas is compressed to a pressure in the range of 1.1 to 50 bar abs.